Large-scale Wastewater Treatment Research Articles

Engineering the S-scheme heterojunction between NiFeAl - LDH and BiOCOOH nanoflower by constructing an interfacial electric field for efficient degradation of levofloxacin under visible light

The antibiotic levofloxacin (LVF), utilized across the world during the COVID-19 pandemic, presents a notable concern in environmental safety owing to its deposition in water bodies. This work reports the engineering of S-scheme heterojunction, NiFeAl LDH coupled with BiOCOOH nanoflower by constructing an interfacial electric field for efficient degradation of LVF under visible light. The scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis reveal the uniform decoration of NiFeAl LDH flakes over flowers like BiOCOOH and the high crystallinity is confirmed with SAED pattern distribution. The construction of an interfacial electric field was confirmed by X-ray photoelectron microscope (XPS) analysis. The X-ray diffraction (XRD), XPS, and Raman spectroscopy studies were conducted to confirm the purity and chemical bonding nature of the BiOCOOH-NiFeAl LDH nanocatalyst (NFB NCs). The band gap of materials was calculated to be 3.38 and 2.03 eV for BiOCOOH and NiFeAl LDH respectively. The NFB NCs showed remarkable performance of 95.2 % than its pristine BiOCOOH (35.4 %) and NiFeAl LDH (18 %). ESR and scavenging studies identified the major involvement of •OH, O2•- and h+ in the process. The intermediates formed during the degradation were examined by using GC–MS and a possible degradation pathway was proposed. Furthermore, the toxicity analysis using the ECOSAR program demonstrates NFB NCs safety level for extensive wastewater treatment. The stability of the NCs over six cycles and magnetic removal properties showcased their potential for large-scale wastewater treatment applications. This comprehensive study highlights the importance of LDH in advancing photocatalytic materials for environmental remediation and paves a way for manufacturing innovation.

Understanding the carbendazim adsorption from water using biochar derived from apple pomace and industrial wastewater sludge: experimental and DFT approaches.

Biochars derived from apple pomace (AP-BC) and industrial wastewater sludge (IS-BC) were used to investigate adsorption performance and mechanism for removing carbendazim from water and compare its performance with commercial biochar (commercial BC). The results showed that the adsorption capacity of AP-BC and IS-BC were 76 mg g-1 and 82 mg g-1 respectively that was comparable with the commercial BC (80 mg g-1). The adsorption kinetics and isotherms were best described by the Pseudo-second-order and Langmuir models. Thermodynamic analysis suggested thathigher temperatures can enhance the mobility of molecules, increased mobility facilitates more frequent and stronger interactions between the adsorbate molecules and the surface of the adsorbent material, leading to greater adsorption capacity. Density functional theory (DFT) calculations confirmed carbendazim's weak electrophilic nature, supporting the primary physisorption mechanism. Even after five cycles of recycling, both biochars maintained a consistent carbendazim removal efficiency of around 82%, highlighting their high reusability. In this study, the examination of waste-derived biochar's economic feasibility revealed that using biochars derived from waste biomass for large-scale wastewater treatment applications is an economically viable choice.

Application of natural earth-based materials as adsorbents for the treatment of chromium (VI)-contaminated tannery wastewater: Box-Behnken and fixed-bed column optimization

This study focuses on the application of earth materials (gravel, clay, zeolite, lime rock, sea shell (Diplodonta)) as adsorbents for the removal of chromium (VI) from tannery wastewater. The removal efficiencies and adsorption capacities of chromium (VI) followed this order: pristine lime rock (63.59 %, qe: 65.5 mg/g)> pristine gravel (48.88 % and 50.4 mg/g)> pristine sea shell (39.03 %, qe: 40.2 mg/g)> pristine zeolite (38.5 %, qe: 39.7 mg/g) > pristine clay (33.55 %, qe: 34.5 mg/g). Lime rock and gravel gave the highest chromium (VI) adsorption capacities and hence, were used in subsequent experiments. Employing Box-Behnken design through response surface methodology, gravel exhibited the highest adsorption capacity (40.7 mg/g) at pH 4, and lime rock (56.1 mg/g) at pH 2, with initial chromium (VI) concentration of 150 mg/L and 11-hour contact time. Scanning electron microscopy and Brunauer–Emmett–Teller analysis showed a lack of pores on both adsorbents suggesting electrostatic attraction as the primary removal mechanism. Best-fitted models were Dubinin-Radushkevich and Temkin isotherms for lime rock and gravel, respectively, while pseudo-first-order kinetics suited both. Thermodynamics calculations showed adsorption is exothermic for lime rock and endothermic for gravel. Application of lime rock in fixed-bed column study showed the highest removal percentage and adsorption capacity (16.64 %, qe: 2.3 mg/g). Applying optimum conditions from column study to synthetic tannery wastewater achieved 63.61 % removal and adsorption capacity (qe: 12.7 mg/g) at 150 mg/L initial chromium (VI) concentration. Regeneration of the adsorbents after 3 cycles maintained strong adsorption capacity. The cost-effective, easily-prepared adsorbent underscores its potential for large-scale wastewater treatment.

Enhancing nitrogen removal performance using immobilized aerobic denitrifying bacteria by modified polyvinyl alcohol/sodium alginate (PVA/SA)

Aerobic denitrification has emerged as a promising and efficient method for nitrogen removal from wastewater. However, the direct application of aerobic denitrifying bacteria has faced challenges such as low nitrogen removal efficiency, bacterial loss, and poor stability. To address these issues, this study developed a novel microbial particle carrier using NaHCO3-modified polyvinyl alcohol (PVA)/sodium alginate (SA) gel (NaHCO3-PVA/SA). This carrier exhibits several advantageous properties, including excellent mass transfer efficiency, favorable biocompatibility, convenient film formation, abundant biomass, and exceptional pollutant treatment capacity. The carrier was modified with 0.3% NaHCO3, 8.0% PVA, and 1.0% SA, resulting in a remarkable 3.4-fold increase in the average pore diameter and a 12.8% improvement in mass transfer efficiency. This carrier was utilized to immobilize the aerobic denitrifying bacterium Stutzerimonas stutzeri W-2 to enhance nitrogen removal (NaHCO3-PVA/SA@W-2), resulting in a NO3−-N removal efficiency of 99.06%, which was 21.39% higher than that without modification. Compared with the non-immobilized W-2, the degradation efficiency was improved by 43.70%. After five reuses, the NO3−-N and TN removal rates remained at 99% and 93.01%, respectively. These results provide a solid foundation for the industrial application of the modified carrier as an effective tool for nitrogen removal in large-scale wastewater treatment processes.

Macro-manufacturing robust and stable metal-organic framework beads for antibiotics removal from wastewater

Metal-organic frameworks (MOFs) have shown great prospects in wastewater remediation. However, the easy aggregation, difficult separation and inferior reusability greatly limit their large-scale application. Herein, we proposed a facile, green and low-cost strategy to construct robust and stable MOF-based hydrogel beads (Fe-BTC-HBs) in a gram scale, and employed them to remove antibiotics from wastewater. As a result, the Fe-BTC-HBs demonstrated outstanding adsorption capacity for both ofloxacin (OFL) and tetracycline (TC) (281.17 mg/g for OFL and 223.60 mg/g for TC) under a near-neutral environment. The main adsorption mechanisms of OFL and TC were hydrogen bonding and π‐π stacking interaction. Owing to its macroscopic granule and stable structure, Fe-BTC-HBs can be separated rapidly from wastewater after capturing antibiotics, and more than 85% adsorption capacity still remained after six cycles, while the powdered Fe-BTC only showed less than 6% recovery efficiency with massive weight loss (around 92%). In real industrial effluent, the adsorption performance of Fe-BTC-HBs toward two antibiotics exhibited negligible decreases (2.9% for OFL and 2.2% for TC) compared with that in corresponding solutions. Furthermore, Fe-BTC-HBs also had appealing economic and environmental benefit. Overall, the macro-manufactured MOF beads have the promising potential for the large-scale wastewater treatment.

Reprocessing and Resource Utilization of Landfill Sludge—A Case Study in a Chinese Megacity

In the past, due to improper sludge treatment technology and the absence of treatment standards, some municipal sludge was simply dewatered and then sent to landfills, occupying a significant amount of land and posing a serious threat of secondary pollution. To free up land in the landfill area for the expansion of a large-scale wastewater treatment plant (WWTP) in Shanghai, in this study, we conducted comprehensive pilot research on the entire chain of landfill sludge reprocessing and resource utilization. Both the combination of polyferric silicate sulfate (PFSS) and polyetheramine (PEA) and the combination of polyaluminum silicate (PAS) and polyetheramine (PEA) were used for sludge conditioning before dewatering, resulting in dewatered sludge with approximately 60% moisture content. The combined process involved coagulation and sedimentation, flocculation, and oxidation to treat the leachate generated during dewatering. The treatment process successfully met the specified water pollutant discharge concentration limits for the leachate, with the concentration of ammonia nitrogen in the effluent as low as 15.6 mg/L. Co-incineration in a power plant and modification were applied to stabilize and harmlessly dispose of the dewatered sludge. The coal-generating system ran stably, and no obvious problems were observed in the blending process. In the modification experiment, adding 5% to 7% of the solidifying agent increased the sludge bearing ratio by 53% and 57%, respectively. This process effectively reduced levels of fecal coliforms and heavy metals in the sludge but had a less noticeable effect on organic matter content. The modified sludge proved suitable for use as backfill material in construction areas without requirements for organic matter. The results of this study provide valuable insights for a completed full-scale landfill sludge reclamation and land resource release project.

Enhanced heterogeneous electro-Fenton process for degradation of rhodamine B: FeOCl/CF@AB composite cathode with superior efficiency and sustainability

With the growing environmental concerns and increasing demand for clean energy, the synthesis of Stable and efficient heterogeneous Electro-Fenton catalysts gains significant attention in the market. We present a novel FeOCl/CF@AB composite cathode designed for efficient heterogeneous electro-Fenton degradation of rhodamine B. The composite cathode exhibits remarkable catalytic performance, outperforming the raw carbon felt electrode, and achieving significantly higher rhodamine B degradation rates. The incorporation of acetylene black encapsulation provides excellent stability, preserving the FeOCl active sites from corrosion and ensuring sustained catalytic activity even after multiple reuse cycles. The electron penetration mechanism on the FeOCl/CF@AB cathode is elucidated through density functional theory calculations, revealing spontaneous O2 activation and H2O2 generation. Electron transfer between Fe(II) species and the acetylene black shell facilitates these processes. The presence of •OH species supports the degradation of rhodamine B to intermediates and mineralization to CO2 and H2O. Furthermore, LC-MS analysis unveils the detoxification effect of the electro-Fenton process with FeOCl/CF@AB, presenting reduced developmental toxicity of degradation intermediates. Economic cost analysis demonstrates the feasibility and cost-effectiveness of the FeOCl/CF@AB cathode for large-scale wastewater treatment applications. In conclusion, the FeOCl/CF@AB composite cathode showcases stability and efficiency, offering a promising and sustainable electro-Fenton technology for dye wastewater treatment.

Superhydrophilic-superhydrophobic integrated system based on copper mesh for continuous and efficient oil-water separation.

In petroleum, petrochemicals, metallurgy, and chemical industries, a significant volume of oily wastewater is unavoidably generated throughout the production processes. This not only harms the environment but also brings about diverse adverse effects on social and economic progress. In this study, copper mesh separation membranes exhibiting superhydrophobicity and superhydrophilicity/underwater superoleophobicity were fabricated through in situ oxidation, chemical vapor deposition, and other physical and chemical modification techniques. Moreover, copper meshes possessing contrasting wetting properties were incorporated into a system combining superhydrophilicity and superhydrophobicity enabling the continuous and efficient separation of mixed oil-water liquids. The separation efficiency of both the superhydrophobic and superhydrophilic membranes surpassed 99.0% and remained above 97.0% after 15 days of continuous use, showcasing the remarkable effectiveness and durability of the integrated system design. This research presents a straightforward and cost-effective design approach for the large-scale treatment of oily wastewater in industrial settings, which is expected to have extensive applications in practical production.

Facile removal of caffeine in 30 seconds using tea waste-derived porous carbon: Effect of surface area and adsorption technique

BackgroundThe release of contaminants from various pharmaceutical sources into water bodies has severely polluted the resources, making them unfit for utilization. Among the pharmaceutical wastes, caffeine has been identified as a serious pollutant due to its widespread consumption by the general public. Biomass-derived porous materials have been considered a suitable adsorbent material for wastewater treatment, owing to their low cost, reusability, and eco-friendly nature. However, the main drawback of adsorbents has been the low maximum adsorption capacity, which has not been given enough attention. MethodsIn this work, we have synthesized porous carbon from tea waste with high specific surface area (2260.82 m2/g) by activating with KOH in nitrogen atmosphere. Further, adsorption studies were performed using shaker and spin column technique. SignificanceThe material was used to remove caffeine in 30 s, using the spin column technique. The material can be recycled with the same spin column and can be reused up to three cycles without a decrease in performance. The maximum adsorption capacity of caffeine at room temperature was found to be 491.4 mg/g, outperforming many reported adsorbents. When considered together, this group of materials has the potential to be used as a cost-effective remedy for environmental-related concerns, especially for large-scale wastewater treatment applications.

Restructuring anaerobic hydrolysis kinetics in plant-wide models for accurate prediction of biogas production

In this study, the effect of anaerobic hydrolysis rate on biogas production was investigated with mesophilic digesters in seven large-scale wastewater treatment plants. A linear correlation was determined between the percentage of primary sludge mass in the total sludge fed to the digester and the overall anaerobic hydrolysis rate. The anaerobic hydrolysis rate of primary sludge was determined to be three times higher than that of biological sludge. The reduction factors for anaerobic hydrolysis (ηHYD,ana) were identified in the range of 0.11–0.30 which is lower compared to the recommended range (0.30–0.50) given in the literature. This study proposes a new model approach where anaerobic degradation kinetics of influent originated (XB) and decay originated (XB,E) particulate biodegradable organics are separated. Current plant-wide models with a single kinetic expression required recalibration of the model for calculating biogas flowrate for each treatment facility with different primary and secondary sludge ratios fed to the digesters. The new model structure is able to predict biogas production of all wastewater treatment plants without any recalibration effort by segregating degradation kinetics of two particulate biodegradable organic fractions (XB, XB,E).

Efficient purification of graphite industry wastewater by a combined neutralization-coagulation-flocculation process strategy: Performance of flocculant combinations and defluoridation mechanism

The wastewater generated by the graphite industry exhibits high acidity and contains elevated concentrations of toxic ions, posing challenges for its efficient and cost-effective treatment. This study presents a novel approach for treating graphite industry wastewater, involving a synergistic process that combines NaOH neutralization, Ca(OH)2 mid-stage coagulation, and compound agent flocculation. The results showed that when pH = 2 was adjusted with NaOH and continued to pH = 8 with Ca(OH)2, the amount of precipitation produced was 62% lower than that of the conventional Ca(OH)2 coagulation process. Based on the defluoridation mechanism, polyaluminum chloride sulfate (PACS) and poly(dimethyldiallylammonium chloride) (PDMDAAC) were identified as the best compound flocculants. The turbidity and fluoride removal efficiencies of raw water reached 99.37% and 99.80%, respectively, when the mass ratio was m(PACS:PDMDAAC) = 9:1, the stirring rate was 150 rpm, and the coagulant dosage was 170 mg/L. By using X-ray powder diffractometer (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) characterization, the flocculation-defluoridation mechanism of PACS in combination with PDMDAAC was examined for its synergistic effect. The flocculation-defluoridation mechanism confirmed that the adsorption complexation of Al3+ on F- is significant in the removal of low concentrations of fluoride ions. Practical applications have proved that this treatment strategy can effectively solve the problems of excessive sludge mass and low removal rate of fluoride and metal ions in graphite industrial wastewater treatment. This process provides a new idea to promote the application of combined flocculants in the large-scale treatment of industrial wastewater.

Assessing the Degradation of Safety Management Performance in Large Construction Projects: An Investigation and Decision Model Based on Complex Network Modeling

Modern safety control theory suggests that the accumulation of safety management defects at the organizational level can lead to a degradation in the overall safety management performance. This problem is exacerbated by the increasing complexity of safety management in large construction projects. The theoretical frameworks proposed by existing studies can provide generalized guidance for identifying safety management defects, but they are not flexible enough to address the complexity of a safety management system (SMS) in specific large construction projects. This study proposed an investigation and decision model based on a complex network model of SMSs. The main purpose was to accurately assess the degradation of safety management performance through the comprehensive identification of safety management defects for large construction projects. The functional components and their interactions in SMSs were graphically represented in a complex network using the fuzzy DEMATEL technique. Based on this, deep-seated safety management defects were identified by tracing the path of influence between the functional components and their roots. Furthermore, the results of this identification were used to support the assessment of the degradation of the safety performance of the overall SMS. The proposed model was verified with a large-scale wastewater treatment plant construction project in Lanzhou City, China. The degradation of the functional components could be presented in a complex visual network map to facilitate an understanding of the weak points or risk-sensitive areas throughout the SMS. Especially in the case of false safety perceptions, deep-seated safety management defects can be identified in time to prevent a sudden collapse of the SMS through early warnings. In addition, it also facilitates timely short-term improvement strategies and systematic long-term improvement strategies for long-term sustainability and increased resilience.

Facile fabrication and application of highly efficient reduced graphene oxide (rGO)-wrapped 3D foam for the removal of organic and inorganic water pollutants.

The pace of water contamination is increasing daily due to expanding industrialisation. Finding a feasible solution for effectively remediating various organic and inorganic pollutants from large water bodies remains challenging. However, a nano-engineered advanced hybrid material could provide a practical solution for the efficient removal of such pollutants. This work has reported the development of a highly efficient and reusable absorbent comprising a porous polyurethane (PU) and reduced graphene oxide (rGO) nanosheets (rGOPU) for the removal of different organic oils (industrial oil, engine oil and mustard oil), dyes (MB, MO, RB, EY and MV) and heavy metals (Pb(II), Cr(VI), Cd(II), Co(II) and As(V)). The structure, morphology and properties of the rGOPU hybrid absorbents were analysed by using Raman spectroscopy, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunner-Emitte-Teller (BET) analysis. The rGOPU possessed both superhydrophobicity and superoleophilicity with water and oil contact angles of about 164° and 0°, respectively. The prepared rGOPU has demonstrated an excellent oil-water separation ability (up to 99%), heavy metals removal efficiency (more than 75%), toxic dye adsorption (more than 55%), excellent recyclability (> 500 times for oils), extraordinary mechanical stability (90% compressible for > 1000 cycles) and high recoverability. This work presents the first demonstration of rGOPU's multifunctional absorbent capacity in large-scale wastewater treatment for effectively removing a wide variety of organic and inorganic contaminants.

Research Progress of Industrial Heavy Metal Wastewater Treatment Process

With the rapid development of modern industry, the types and emissions of heavy metal wastewater are also increasing day by day. Heavy metal wastewater is non biodegradable, and discharge standards are also updated and iterated with people's continuous requirements for health. Based on the current situation of industrial heavy metal wastewater treatment in China, this paper summarizes the sources and treatment status of heavy metal wastewater, as well as the commonly used technologies and processes for industrial wastewater treatment from traditional to modern at home and abroad, introduces the advantages and disadvantages of physical, chemical and biological treatment methods for industrial wastewater containing heavy metals in practical applications, and looks forward to the development trend of Advanced oxidation process and biological treatment methods. The biological treatment method has the characteristics of rich raw materials, environmentally friendly and pollution-free, but at present, the research on biotechnology is not mature and its application is not widespread. If the system is applied to industrial treatment of heavy metal wastewater, further research is still needed. There are few heavy metal wastewater treatment equipment or systems developed from heavy metal wastewater treatment processes, and the issues of continuous operation, automation, and large-scale treatment of heavy metal wastewater still need to be explored. There is also room for development in the field of resource development and utilization by extracting and recovering heavy metals from sludge after heavy metal wastewater treatment. This article reviews the methods for treating heavy metal wastewater and evaluates them, with the aim of pointing out research directions and providing practical application references for the large-scale industrial development of industrial heavy metal wastewater in the future.

Synergistic degradation and degradation pathways of methylene blue by plasma process combined with cavitation impinging stream reactor based on hydrodynamic cavitation

The plasma process is an advanced oxidation technique that boasts high efficiency and low cost. A combination of the plasma process with a cavitation impinging stream (CIS) reactor has been developed to investigate the degradation characteristics of methylene blue dye wastewater. The results indicate that under a pressure of 1.40 MPa and an impinging distance of 40 mm, the CIS reactor achieved a degradation rate of 52.83%, which was twice as much as self-excited oscillation cavitation alone. Furthermore, it was found that the optimum solution concentration for this reaction was 5.70 mg/L. Combining a plasma apparatus with a CIS reactor resulted in a degradation rate of 94.06% within 60 min, with a synergy index of 3.13. Intermediate products generated during the HC+plasma treatment were analyzed using liquid chromatography-mass spectrometry. Based on experimental and theoretical analyses, two possible pathways for methylene blue degradation were proposed. This study presents novel insights into the degradation pathway of methylene blue. The CIS+Plasma technology exhibits superior efficiency, higher cavitation yield, and lower operational costs, rendering it a viable option for large-scale wastewater treatment applications.

Characterization of calcined red soil applied in the removal of methylene blue dye from wastewater to produce a hybrid pigment

AbstractWe obtained natural red soil (RS), rich in iron, from the region of Palotina in the state of Paraná, Brazil. The RS sample was purified by suspension in water and sieved to remove plant particulates. It was then treated thermally at 800°C to remove organic volatiles; this sample was called RS800. The samples were characterized using X-ray diffraction, X-ray fluorescence, infrared and electronic spectroscopy, ζ-potential analysis and scanning electron microscopy. Colorimetric studies were performed according to the CIEL*a*b* system. Tests have shown that RS800 has the ability to remove methylene blue (MB) dye from wastewater. Thus, it was used as an adsorbent at various temperatures (25, 35, 45°C). According to the Langmuir model, the maximum adsorption capacity (qmax) was 23.256 mg g–1 (25°C). Unexpectedly, increasing temperature reduced qmax to 21.659 mg g–1 at 35°C and to 21.186 mg g–1 at 45°C. Therefore, RS800 must be used at room temperature (25°C), making its application in large-scale wastewater treatment feasible. After using RS800 as an adsorbent, the solids were filtered, dried, pulverized, and used as hybrid pigments in commercial white paints. Pigmented paints were used to paint a plaster specimen and colorimetric measurement was performed. These paints were tested for colour stability in acidic and alkaline environments. The results indicate that RS800 is efficient in the treatment of water contaminated with cationic dyes and can be reused as a hybrid pigment.

Microbial fuel cell: Interplay of energy production, wastewater treatment, toxicity assessment with hydraulic retention time

Microbial fuel cell (MFC) operation under similar conditions to conventional methods will support the use of this technology in large-scale wastewater treatment. The operation of scaled-up air-cathode MFC (2 L) fed with synthetic wastewater (similar to domestic) in a continuous flow was evaluated using three different hydraulic retention times (HRT), 12, 8, and 4 h. We found that electricity generation and wastewater treatment could be enhanced under an HRT of 12 h. Additionally, the longer HRT led to greater coulombic efficiency (5.44%) than MFC operating under 8 h and 4 h, 2.23 and 1.12%, respectively. However, due to the anaerobic condition, the MFC was unable to remove nutrients. Furthermore, an acute toxicity test with Lactuca sativa revealed that MFC could reduce wastewater toxicity. These outcomes demonstrated that scaled-up MFC could be operated as a primary effluent treatment and transform a wastewater treatment plant (WWTP) into a renewable energy producer.

Performance and economic evaluation of a pilot scale embedded ends-free membrane bioreactor (EEF-MBR)

In this work, an embedded ends-free membrane bioreactor (EEF-MBR) has been developed to overcome the fouling problem. The EEF-MBR unit has a novel configuration where a bed of granular activated carbon is placed in the bioreactor tank and fluidized by the aeration system. The performance of pilot-scale EEF-MBR was assessed based on flux and selectivity over 140h. The permeate flux fluctuated between 2 and 10 L.m-2.h-1 under operating pressure of 0.07-0.2bar when EEF-MBR was used to treat wastewater containing high organic matter. The COD removal efficiency was more than 99% after 1h of operating time. Results from the pilot-scale performance were then used to design a large-scale EEF-MBR with 1200 m3.day-1 capacity. Economic analysis showed that this new MBR configuration was cost-effective when the permeate flux was set at 10 L.m-2.h-1. The estimated additional cost for the large-scale wastewater treatment was about 0.25 US$.m-3 with a payback period of 3years. KEY POINTS: • Performance of new MBR configuration, EEF-MBR, was assessed in long term operation. • EEF-MBR shows high COD removal and relatively stable flux. • Cost estimation of large scale shows the cost effective EEF-MBR application.

Estimating the effect of wastewater treatment facility’s operating failure due to disaster on river’s water quality

The study investigated a disaster countermeasure system for wastewater treatment facilities, focusing on both structural and non-structural responses. As part of the non-structural countermeasures, the effect of untreated effluent from damaged wastewater treatment facilities due to disasters on the river was simulated. The results showed that untreated effluent from the wastewater treatment facility did not affect the river's water quality due to its low flowrate. However, it had a significant impact on the water quality of the river when the flowrate of untreated effluent had increased. The study also evaluated the efficiency of movable treatment units as part of structural countermeasures to respond to damaged wastewater treatment facilities. The researchers simulated the effect of effluent treated by movable treatment units on the river. The findings indicated that movable treatment units were effective in reducing the impact on the river's water quality for small-scale wastewater treatment facilities. However, for mid and large-scale wastewater treatment facilities, disaster countermeasures should prioritize ensuring sufficient storage space for untreated water rather than relying on other emergency response devices, such as movable treatment units tested in this study, to respond to disasters.

Process optimization for textile industry-based wastewater treatment via ultrasonic-assisted electrochemical processing

The treatment of industrial wastewater at a reasonable cost and in a sustainable approach is a major challenge. The primary objective of this study is to perform textile wastewater treatment by exploring the ultrasonic-assisted electrochemical (UEC) process with parameter optimization. Statistical modeling has been carried out in order to investigate the influence of operating parameters, including pH (4–10), current density (5–20 mA/cm2), electrolysis time (10–30 min), and ultrasonic power (0–500 watt) on color, chemical oxygen demand (COD), and turbidity removal efficiency. The combination of response surface methodology (RSM) and artificial neural network (ANN) based statistical models are applied to predict and examine the reliance of the operating parameters on removal efficiencies. The results validate that at optimal operating condition (pH 7.3, current density 15.7 mA/cm2, processing duration 21.5 min, and ultrasonic power 420 W), the actual removal efficiencies of color, COD, and turbidity was 97%, 66%, and 79% respectively. The central composite design (CCD) based RSM model predicts the removal efficiencies of color, COD, and turbidity was 93.9 %, 63.6 %, and 77.1 %, respectively. In contrast, the ANN model predicts removal efficiencies of color, COD, and turbidity of 99.3%, 82.1%, and 78.7%, respectively at optimized operating conditions. The results indicated that the ANN model had a greater coefficient of determination (R2) value and smaller mean square error (MSE) than RSM model, showing that ANN is preferable at forecasting response, while RSM accurately predicts impacts of operating parameters. The present manufacturing process with statistical optimization techniques may be envisioned for the large-scale treatment of industrial wastewater.